Well obviously there's the gff arcade, but half of the games are lol.
If you're looking for shooters try
going here as there's a billion+ listings of PC shooters available around the internets. I don't know of any that aren't exactly time consuming (even the touhou shooters are relatively time consuming, you won't want to play one for 10 minutes alone if you're going to try), but there's always Every Extend.
It's basically a variant type of shooting game where you don't shoot, but deliberately blow yourself up. Your explosion hits other enemies, which triggers a chain, which could possibly hit other enemies, and so forth. The entire game is based around chaining from suicide, and you have the option of killing yourself a certain amount of times.
It doesn't really fit into either catagory you're aiming for but I'd still try it out if you're wanting a quick game.
Jam it back in, in the dark.
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